Semiconductor structures are structures that are used or formed in the fabrication of semiconductor devices. Semiconductor devices include, for example, electronic signal processors, electronic memory devices, photoactive devices, and microelectromechanical (MEM) devices. Such structures and materials often include one or more semiconductor materials (e.g., silicon, germanium, a III-V semiconductor material, etc.), and may include at least a portion of an integrated circuit.
There are many types of electronic memory devices being used or under development. For example, dynamic random-access memory (DRAM) and NAND Flash memory have been used for many years. Other memory types, often referred to as “emerging memory,” are currently under development and may replace or supplement DRAM and NAND Flash memories as they become technologically and economically feasible. Some example emerging memory types include resistive random-access memory (RRAM), phase change memory (PCM), and magnetoresistive random-access memory (MRAM).
Some emerging memory types require relatively high electrical current density (measured in amperes per unit area) to properly write, read, and/or erase data to memory cells thereof. The relatively high electrical current density requires a relatively large amount of electrical current for proper operation. In addition, the large amount of current requires memory cell access devices (e.g., transistors, diodes) to be formed of a sufficient size to handle such electrical currents without failure.
In one known PCM configuration, an electrical contact having a thickness of about 7.5 nm is formed by depositing a metal on a sidewall of a structure. The metal is then patterned by photolithography techniques to form the electrical contact having a cross-section of about 7.5 nm (defined by the thickness of the metal) by about 22 nm (defined by the photolithography). A top portion of the electrical contact is recessed, and PCM cell material is introduced into the recess using a chemical vapor deposition (CVD) process.